Clear The Lof (Bits) Alarm; Lof (Stmn) - Cisco ONS 15600 SDH Troubleshooting Manual

2.6.117 LOF (STMN)

Clear the LOF (BITS) Alarm

Verify that the framing and coding match between the BITS input and the TSC card by completing the
Step 1
following steps:
a.
b.
c.
d.
e.
f.
Step 2 Ensure that the BITS clock is operating properly.
Always use the supplied electrostatic discharge wristband when working with a powered
Caution
ONS 15600 SDH. Plug the wristband cable into the ESD jack located on the lower-right edge of the shelf
assembly.
If the alarm does not clear, log into the Technical Support Website at http://www.cisco.com/techsupport
Step 3
for more information or call Cisco TAC (1 800 553-2447).
2.6.117 LOF (STMN)
The Line Loss of Frame Alignment alarm occurs when a port on the reporting traffic (STM-N) card has
an LOF. LOF indicates that the receiving ONS 15600 SDH has lost frame delineation in the incoming
data and when the SDH overhead loses a valid framing pattern for three milliseconds. Receiving two
consecutive valid A1/A2 framing patterns clears the alarm.
LOF on a traffic card is sometimes an indication that the port reporting the alarm expects a specific line
rate and the input line rate source does not match the input line rate of the optical receiver.
If the port is in 1+1 protection and successfully switches, the alarm severity is MN, NSA. If the port is
unprotected or if protection switching is prevented, the severity is CR, SA.
Cisco ONS 15600 SDH Troubleshooting Guide, R8.0
2-82
Find the coding and framing formats of the external BITS timing source. This should be in the user
documentation for the external BITS timing source or on the external timing source itself.
Click the node view Provisioning > Timing > BITS Facilities tabs.
Verify that the Coding setting matches the Coding setting of the BITS timing source (either B8ZS
or AMI).
If the coding does not match, click Coding to display a drop-down list. Choose the appropriate
coding.
Verify that the Framing matches the framing of the BITS timing source (either ESF or SF [D4]).
If the framing does not match, click Framing to display the drop-down list. Choose the appropriate
framing.
In the Timing window, the B8ZS coding field is normally paired with ESF in the Framing
Note
field, and the AMI coding field is normally paired with SF (D4) in the Framing field.
Default Severity: Critical (CR), Service-Affecting (SA)
Logical Object: STMN
Chapter 2 Alarm Troubleshooting
July 2010